"Johnstoun, an old possession of the Nisbets, came from them to the Wallaces, continued six generations a house of good account, now decayed".

W Macfarlane 1907

Johnstone Castle, now situated in a modern housing scheme, was originally named "Easter Cochran" and owned by the family of that ilk, its name changed in 1733 when it was acquired by the Houstons of Johnstone. they added to and altered the former mainly 16th century fortalice in the years that followed. Now that the estate has been taken over by the burgh, most of the extended mansion has been pulled down and only the original part is left, though much scarred by 19th century 'improvements'. It is now used as a store.

The castle as it now stands is L-shaped and consists of a comparatively little-altered main block of three storyes and a garret, lying E-W, with a wing, now built in the form of a massive Gothic tower, projecting N and rising a storey higher. Apart from two tiny windows at basement level, and others built up, the wing has been very much altered.

The hall, on the first floor of the main block, has also been much altered, but still retains a garderobe and a very deep window embrasure, giving the impression of a nucleus older than the 16th century.